<template>
  <div class="spec-preview" @mousemove="makeMove">
    <img :src="imgUrl || skuDefaultImg" />
    <div class="event"></div>
    <div class="big">
      <img :src="imgUrl || skuDefaultImg" ref="bigImg" />
    </div>
    <div class="mask" ref="mask"></div>
  </div>
</template>

<script>
export default {
  name: 'Zoom',
  props: ['skuDefaultImg'],
  data() {
    return {
      // data中数据进行数据代理时,props还没有接收参数
      imgUrl: this.skuDefaultImg,
    }
  },
  // computed: {},
  mounted() {
    //使用事件总线绑定事件时,需要使用箭头函数,使得其中的this指向当前实例, 以修改当前实例的数据
    this.$bus.$on('changeBigImg', (url) => {
      this.imgUrl = url
    })
  },
  methods: {
    makeMove(e) {
      // let make = e.target
      let mask = this.$refs.mask
      let bigImg = this.$refs.bigImg
      let makeMoveSize = {
        x: e.offsetX,
        y: e.offsetY,
      }
      let makeMove = {
        x: makeMoveSize.x - mask.offsetWidth / 2,
        y: makeMoveSize.y - mask.offsetHeight / 2,
      }
      if (makeMove.x < 0) {
        makeMove.x = 0
      } else if (makeMove.x >= e.target.clientWidth - mask.offsetWidth) {
        makeMove.x = e.target.clientWidth - mask.offsetWidth
      }
      if (makeMove.y < 0) {
        makeMove.y = 0
      } else if (makeMove.y >= e.target.clientHeight - mask.offsetHeight) {
        makeMove.y = e.target.clientHeight - mask.offsetHeight
      }
      mask.style.left = makeMove.x + 'px'
      mask.style.top = makeMove.y + 'px'
      bigImg.style.left = -makeMove.x * 2 + 'px'
      bigImg.style.top = -makeMove.y * 2 + 'px'
    },
  },
}
</script>

<style lang="less">
.spec-preview {
  position: relative;
  width: 400px;
  height: 400px;
  border: 1px solid #ccc;

  img {
    width: 100%;
    height: 100%;
  }

  .event {
    width: 100%;
    height: 100%;
    position: absolute;
    top: 0;
    left: 0;
    z-index: 998;
  }

  .mask {
    width: 50%;
    height: 50%;
    background-color: rgba(0, 255, 0, 0.3);
    position: absolute;
    left: 0;
    top: 0;
    display: none;
  }

  .big {
    width: 100%;
    height: 100%;
    position: absolute;
    top: -1px;
    left: 100%;
    border: 1px solid #aaa;
    overflow: hidden;
    z-index: 998;
    display: none;
    background: white;

    img {
      width: 200%;
      max-width: 200%;
      height: 200%;
      position: absolute;
      left: 0;
      top: 0;
    }
  }

  .event:hover ~ .mask,
  .event:hover ~ .big {
    display: block;
  }
}
</style>
